This invention relates to an improvement in a flow stabilizer for a ventilation duct.
Prior flow stabilizers, as exemplified by French Pat. No. 70 12 065, comprised a chamber consisting of a deformable bag, a seat supporting the chamber with a hole permitting air to enter or exit from the chamber, and means adapting the seat to the ventilation duct, so that the orifice is directed upstream. The respective dimensions of the chamber and the section of the duct were such that under the action of pressure differences existing upstream and downstream, the variation of volume of the chamber which resulted therefrom modified the section for the passage of air in the space made between the chamber and the duct. These devices had been designed to stabilize the air flow without amplifying its sudden fluctuations, and consequently without maintaining fluctuating operating conditions in the duct.
Although the bag constituting the chamber was made of an elastic and flexible material, because of the loss of elasticity of this material due to its aging, this stabilizer, was only slightly durable.
To eliminate this drawback, flow stabilizers were developed as shown in French Pat. No. 79 24 829, having elastic means associated with the bag chamber so that the elastic means was housed inside the chamber to provide its return to a minimum volume when the pressure difference between the ventilation duct areas located upstream and downstream from the chamber fell below a predetermined threshold.
Thus, the bag could be formed by molding it in the shape corresponding to its maximum volume, which, with the absence of undercut, facilitated its removal from the mold, and its return to its minimum value was no longer dependent upon its own elasticity. Its life was therefore considerably increased.